Expansion joint



' June 18, 1963 R. R. UNDERHILL 3,093,934

EXPANSION JOINT Filed May 15. 1960 {($4 I? .5 If; 6

9/ 9 IIVV EN TOR.

AM/Iar'a R Una ark /7/ United States Patent Oflice Patented June 18, 1963 3,093,934 EXPANSION JOINT Richard R. Underhill, Midland, Mich., assignor to The Dow Chemical Company, Midland, Mich., a corporation of Delaware Filed May 13, 1960, Ser. No. 29,094 7 Claims. (Cl. 50-172) This invention relates to expansion joints and a method of preparing expansion joints and, more particularly, relates to water-proof roof expansion joints.

Much difliculty has been encountered in the construction of large roofs in providing suitable expansion joints to prevent buckling or deformation of the roof under widely varying ambient temperatures. .Various slide and lap joints have been tried and generally found unsuitable because of leakage during rain and wind storms. Strips of flexible material have been cemented to adjacent edges of the roof sheets or panels and such joints have found limited acceptance. Frequently, such joints fail because of constant flexure in or about the cemented area and suffer from added disadvantage that insulation is difllcult or impossible to install.

Current roof deck construction frequently calls for the application of prefabricated sheets or panels containing insulation between external surfaces. .These panels often employ clips or other means by which they may be secured to the supporting roof framework. The simple provision of a flexible strip for an expansion joint on the roof built from prefabricated sheets is generally inadequate as the strips are generally subject to damage and represent a substantial noninsulated area. The inclusion of thermal insulating material under such joints, wherein the' insulating material is subjected to compression between the roof deck sheets, usually results in rapid failure of the material after a few compressive cycles.

Thus, it would be advantageous if weather-tight, durable, expansion joints were provided suitable for use in roofing.

It,would be further advantageous if such an expansion joint were provided with lasting thermal insulation.

It would be beneficial if such a joint were easily fabricated and not readily subject to physical damage.

These advantages and other benefits may be obtained by providing an expandable roofing joint comprising a pair of sheets having upper and lower faces and adjacent edges; means defining an upwardly facing recess adjacent the edges of the .upper faces of the adjacent edges of said pair of sheets; a generally U-shaped flexible foamed plastic member, having one leg positioned in each of said recesses; a flexible strip passing over said U-shaped member and ailixed to each of said sheets.

Further features and advantages of the invention will be more apparent in the following description and specification taken in connection with the accompanying drawing wherein:

FIGURE 1 is an isometric sectional view of an expansion joint in a flat roof deck in accordance with the invention;

FIGURE 2 is a cross-sectional schematic view of an outside corner expansion joint fabricated in accordance with the invention;

FIGURE 3 depicts an inside corner expansion joint; and

FIGURES 4, 5 and 6 illustrate alternative configurations of an upwardly facing recess in the edge of a roof deck sheet.

In FIGURE 1 there is illustrated an isometric view of an expansion joint indicated generally by the reference numeral 10. The joint 10 seals the space 11 between e roof deck sheets 12 and 13. A metal angle 14 is ositioned at the edge of sheet 12, and a similar angle 15 is located at the edge of sheet 13. Immediately adjacent the horizontal leg of the angles 14 and 15 are provided fillet strips 17 and 18. An upwardly facing recess 20 is formed between the vertical leg of angle 14 and fillet strip 17, and a second upwardly facing recess 21 is formed between the vertical leg of angle 15 and the fillet strip 18. A generally U-shaped flexible foam plastic member 23 is positioned with its legs 24 and 25 seated in recesses 20 and 21. :A layer of roofing felt 27 covers the upper surfaces of sheets 12 and 13 and the major face of the filiet strips 17 and 18. A flexible plastic strip 28 overlays the foam insert 23 and the fillet strips 17 and 18 and is secured to the roofing felt by an adhesive (not shown). rThe edges 29 and 30 of the flexible plastic strip 28 are overlayed by roofing felt edge strips 31 and 32 and are subsequently secured in place by suitable adhesive (not shown).

. FIGURE 2 represents a schematic cross-sectional view of an outside ninety-degree expansion joint generally indicated by the reference numeral 40. The joint 40 is constructed in a manner similar to joint 10 of FIGURE 1 and comprises sheets 41 and 42 having afiixed near their edges angles 44 and 45 and fillet strips 47 and 48 spaced from the vertical legs of the angles 44 and 45 forming the recesses 49 and 50. A generally U-shaped foamed plastic member 51 extends from recesses 49 and 50, and the entire joint is overlayed with flexible plastic strip 53.

There is depicted in FIGURE 3 a schematic crosssectional View of an inside ninety-degree joint in accordance with the invention generally indicated by the reference numeral 60, wherein the roof deck sheets 61 and 62 are provided with the angles 63 and 64, fillet strips 66 and 67, and generally forming recesses 69 and 70 containing the opposite legs of a generally U-shaped flexible foamed plastic member 71. This assembly is overlayed with a flexible plastic strip 72. FIGURE 4 shows a cross-sectional view of an alternate form which may be employed to provide an upwardly facing recess. A sheet is provided with a groove 81 and fillet strip 82 while in FIGURE 5 a roof deck sheet 85 is provided with a simple rabbet 86.

In FIGURE 6 a roof deck sheet has formed therein a rabbet 91 and a cap strip 92 and provided to form a three-sided recess.

Expansion joints in accordance with the invention may readily be fabricated on the site employing conventional materials of construction.

With reference to FIGURE 1 roofing sheets 12 and 13 may be conventional, built-up steel roofing decking, concrete, plastic foam laminates, wood planking, plywood, or other conventional materials. Angles 14 and 15 may be secured to the edge of roof decking by means of adhesives, bolts, screws, clips, or other fastening means. The fillet or cant strips 17 and 18, if desired, may be fabricated from wood, metal, concrete, or other similar materials of construction and secured in position by conventional fastening means. Roofing felt 27 or other coating material is then applied to cant strips 17 and 18 and roof decking 13 and 14. A flexible foamed plastic member 23 may readily be formed from a flat plank of flexible foamed plastic by manually bending it into a U-shaped configuration and inserting the legs 24 and 25 into the recesses 20- and 21. This assembly is subsequently capped with a flexible flat plastic strip 28 such as that obtained commercially under the trade name SARALOY 40 0, a formulated vinylidine chloride copolymer containing carbon black. Advantageously, this flexible plastic strip 28 covers the entire joint assembly and is secured to the cant strips 17 and 18 and roof decking sheets 13' and 14 by a suitable adhesive. For further assurance of weather resistance, a layer of bituminous adhesive is applied to the edges 29 and 30 of the flexible plastic strip 28, and tapes 31 and 32 of roofing felt is raised over the edges of the plastic strip 28 and the surface of the roof deck sheets 12 and 13. Felt strips 31 and 32 are thencoated with another layer of bituminous mastic. Thus, a sound weather-tight expan sion joint 10 is formed which exhibits no appreciable tendency to deteriorate with time and weather. This joint 10 also provides an excellent insulation between the interior and exterior of the building. I

The expansion joints 40 and 60 illustrated in FIGURES 2 and 3 are fabricated in a manner similar to joint 10. Roof sheets 80', 85, and 90, as shown in FIGURES 4, 5, and 6, may be formed with a groove or rabbet to receive the flexible foam plastic material. 15 of FIGURE 1 may be omitted. The cant strips 17 and- 18 advantageously are employed to reduce the bend necessary in roofing felt 27 where the plastic strip 28 is secured to the roof deck sheets 13 and 14. The cant or fillet strips 17 and 18 advantageously tend to eliminate weather damage caused by snow and ice and also serves to decrease the degree of flexure necessary in the plastic strip 28. V

The retaining lip 92 shown in FIGURE 6 or its mechanical equivalents such as the vertical legs of the angles 14 and 15 is particularly beneficial if there is any possibility of occasional foot traffic over a joint or other mechanical deflecting forces which might be applied directly or indirectly to foamed plastic member 28. Although the rabbet arrangement of FIGURE is often less expensive to install the retaining lip of FIGURES 1, 2, 3, 4, and 6 prevent the legs 24 and 25 of the U-shaped member 23 from becoming displaced from their intended location.

A wide variety of flexible foamed resinous plastic members 28 may be employed in the practice of the invention such as foamed polyethylene, foamed polypropylene, flexible polyurethane foams, and copolymers of ethylene,

foamed polyvinyl chloride, foamed rubber, and similar materials. The cap strip 28 may be prepared from various rubbers which have been formulated to resist exterior exposure plastics such as formulated polyvinyl chloride and polyvinylidene chloride compositions usually incorporating an inert filler such as SARALOY 400 Other flexible material such as flexible impregnated woven fabric, felts, and the like may be employed in the practice of the invention.

The present expansion joint is susceptible of being em bodied with various alterations and modifications differing in detail from that which has been described in the preceding description and specification. Therefore, it is .to be fully understood that all of the foregoing is intended to be merely illustrative and is not to be construed or interpreted as being restrictive or otherwise limiting of the present invention excepting as is set forth and defined in the hereto appended claims.

The angles 14 and" What is claimed is:

1. A roof expansion joint comprising a pair of sheets having first and second faces and adjacent spaced edges, the sheets being capable of movement relative to one another in the plane of each sheet,

a retaining lip at the adjacent edge of each of the sheets and generally normal to the first face a cant strip secured to said first face, spaced from the retaining lip,

the cant'strip being generally parallel to the retaining lip and in cooperative combination with the lip forming a recess,

the cant strip having an inclined surface, the" inclined surface terminating adjacent the first face and remote from the retaining lip, and also terminating at the recess face,

a generally U-shaped flexible foam plastic member having the terminal portion of one ofthe legs positioned in a recess of one of said sheets and the other leg in the other recess of the other sheet,

and a flexible sealing strip passing over the U-shaped member and secured to each sheet and cant strip.

2. A joint in accordance with claim 1, wherein said retaining lip is one leg of a metal angle.

3. A joint in accordance with claim 1, wherein said sheets are coplanar.

4. A joint in accordance with claim 1, wherein said sheets form an outside corner. 7

5. A joint in accordance with claim 1,'wherein said sheets form an inside corner.-

6. A joint in accordance with claim 1, wherein said plastic member is polyethylene foam.

7. A joint in accordance with claim 1, wherein said flexible strip is a copolymer of vinylidene chloride containing carbon black.

References Cited in the file of this patent UNITED STATES PATENTS 132,345 Woolfolk Oct. 15, 1872 2,106,140 Strong 1 Jan. 18, 1938 2,122,869 Morris July 5, 1938 2,220,628 Stedman Nov. 5, 1940 2,234,799 Eason Mar. 11,1941

' 2,730,969 Perry Jan. 17, 1956 2,742,115 Strong Apr. 17, 1956 2,791,527 Gawry-siak May 7, 1957 2,974,078 Petritz et a1. Mar. 7, 1961 2,980,972 Kloote et al'. Apr. 25, 1961 FOREIGN PATENTS 567,364 Italy 1957 

1. A ROOF EXPANSION JOINT COMPRISING A PAIR OF SHEETS HAVING FIRST AND SECOND FACES AND ADJACENT SPACED EDGES, THE SHEETS BEING CAPABLE OF MOVEMENT RELATIVE TO ONE ANOTHER IN THE PLANE OF EACH SHEET, A RETAINING LIP AT THE ADJACENT EDGE OF EACH OF THE SHEETS AND GENERALLY NORMAL TO THE FIRST FACE A CANT STRIP SECURED TO SAID FIRST FACE, SPACED FROM THE RETAINING LIP, THE CANT STRIP BEING GENERALLY PARALLEL TO THE RETAINING LIP AND IN COOPERATIVE COMBINATION WITH THE LIP FORMING A RECESS, THE CANT STRIP HAVING AN INCLINED SURFACE, THE INCLINED SURFACE TERMINATING ADJACENT THE FIRST FACE AND REMOTE FROM THE RETAINING LIP, AND ALSO TERMINATING AT THE RECESS FACE, A GENERALLY U-SHAPED FLEXIBLE FOAM PLASTIC MEMBER HAVING THE TERMINAL PORTION OF ONE OF THE LEGS POSITIONED IN A RECESS OF ONE OF SAID SHEETS AND THE OTHER LEG IN THE OTHER RECESS OF THE OTHER SHEET, AND A FLEXIBLE SEALING STRIP PASSING OVER THE U-SHAPED MEMBER AND SECURED TO EACH SHEET AND CANT STRIP. 